The need for a reliable covering system and particularly a retractable covering system for truck and trailer bodies has long been recognized where the cargo being carried is perishable, a hazardous material, or which could be dangerous to passing motorists such as stones, gravel, asphalt, shale, or any other material which can become a projectile. Moreover, many states are passing laws which mandate the use of covering systems on trucks and trailers. Retractable covering systems have the advantage that they can be operated easily and safely from the ground by one person. They also can be extended and retracted in very little time thereby improving overall efficiency and reducing driver fatigue.
U.S. Pat. Nos. 4,801,171, 4,725,090 and 4,189,178 describe several different truck tarpaulin covering systems which allow a tarpaulin cover to be mechanically extended or retracted from the top portion of a truck trailer. While these retractable cover systems can accomplish their intended purpose once they are installed, they typically require a significant amount of time and effort to install, especially since they are not easily installed by one person. Thus, they are not interchangeable.
Moreover, these systems have a serious drawback if the tarpaulin or its supports become damaged, either during normal operation or during covering and uncovering of the trailer body. It is very difficult to repair or replace these systems if they become damaged and therefore the entire truck can be out of operation for a long period of time until the cover system is completely repaired or replaced. This is because, to replace the cover or the supporting rods, the cables which enable the cover system to be retractable have to be disconnected from all of the supporting bows and these in turn must be disconnected individually from the entire tarp. If a spare tarp is not immediately available, the entire tarp must be sent out for repair even if the damaged area comprises only a small portion of the tarp. Additional delays can occur in repairing the tarp, itself. Even after the tarp is repaired, the whole cover system must be reassembled and reinstalled on the truck trailer, again requiring a significant amount of time and manual labor.
The entire removal and installation process is quite involved and very labor intensive because these tarps can be quite big (typically 10-48 ft. long) and on average are about 34 ft. long and 8-10 ft. wide. In most of these systems, a sleeve is required to be made in the tarp (typically about every 3 ft.) into which each one of the supporting rods must be inserted. This construction results in a very expensive tarp due to the amount of detailed work involved in creating all these pockets. Moreover, it is very tedious and time consuming to insert all of the supporting bows into the tarp pockets as in U.S. Pat. No. 4,189,178 or to connect the tarp to each of the supporting rods as in U.S. Pat. Nos. 4,801,171 and 4,725,090. It is also difficult, due to its weight and bulk, to put the combined tarp and supporting rod assembly onto the truck trailer. Thereafter, the cables by which the cover is extended or retracted must be individually connected to each supporting rod by feeding it through an opening in the end thereof. As a result of this expensive and involved process, many trucks operate with damaged tarps and supporting rods because it is easier and cheaper to use damaged equipment than to incur the time and expense necessary to fix it. However, using damaged tarps permits material to be blown from the truck trailers and allows water damage to the cargo, thereby defeating the purpose of the truck cover system and possibly being a violation of law.
Due to the frequency with which these tarpaulin covering systems become damaged it would be desirable to have a retractable cover system wherein only the damaged portion could easily be removed and replaced without replacing or disassembling the entire cover system. Similarly, such a cover system would be desirable in certain application, even if it were not retractable.